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The Mouth to the Oesophagus
The mouth is the first organ of digestion. Teeth chew our food, physically breaking it down, and the inside of our mouth contains glands that produce saliva – not only when we eat food but also when we’re just thinking about it. Saliva is important. This liquid, which is neutral to slightly acidic, not only starts the chemical process of digestion, but it lubricates each mouthful, helping us to swallow properly. We produce about 1.7 litres (about 60fl oz) of saliva every day. One of the main enzymes contained in saliva is called amylase, which starts breaking starch down into more basic sugars. When we swallow, food enters the first ‘tube’ – the oesophagus, which is about 25cm (10in) long. The oesophagus doesn’t do anything to digest food. Waves of muscle contraction (called peristalsis) help push the food down the oesophagus. These muscular contractions are so strong that you can drink a glass of water while standing on your head.
The Stomach
Food enters the stomach through a ring of muscle (sphincter) that prevents the stomach contents from travelling back up the oesophagus – the one normal exception to this is during vomiting. The stomach is so stretchy that it can hold up to 2 litres (about 70fl oz) of fluid. While food is in the stomach it is subjected to both physical and chemical action. Stomach acids – mostly hydrochloric acid (one of the strongest acids known to man) – reduce the stomach contents to a porridge-like consistency, while the stomach also mechanically ‘churns’ the food during the four hours or so that food stays there. Because the stomach contents are very acidic, we get ‘burning’ sensations when we vomit, have indigestion or gastric reflux, as the contents bubble back up into the oesophagus. After a while, the sphincter muscle (called the pylorus) that holds the lower end of the stomach closed starts to relax, allowing the partly-digested food to trickle out into the first portion of the small intestine.
The Small Intestine
As food is squirted through the pylorus, it enters the first part of the small intestine, the duodenum. Here, more digestive chemicals are introduced, further breaking down the food. Bile, for example, an alkaline substance that is made in the liver, is pumped out by the gall bladder when needed. Bile acts as a detergent and emulsifying agent, breaking fats down into small droplets. Pancreatic enzymes break down carbohydrates and proteins: amylase acts on carbohydrates and trypsin and chymotrypsin help digest proteins. Fats are also further broken down by lipase, another pancreatic enzyme.
The next section of the small intestine, the 3 metre (10ft) long jejunum, is where most of the nutrients released from food start to be absorbed. The walls of the jejunum are completely covered with tiny finger-like projections called villi. Millions of these millimetre-high folds line the intestinal walls, their purpose being to massively increase the surface area to make absorption of nutrients into the bloodstream effective (see figure overleaf). If the small intestines didn’t have villi, they would need to be about 2 miles long to do the same job – in fact, they are only about 6 metres (20ft) long. After the jejunum comes another 3 metre (10ft) long section of small bowel commonly known as the ileum. Although there are still many villi here, there are fewer than in the jejunum. The ileum continues to absorb nutrients into the bloodstream, but the focus here is more on water and salts; as food progresses through the small bowel, the consistency of it becomes thicker and more ‘sludgy’. In the very last part of the ileum, vitamin B12 is absorbed.
The Large Intestine – the Colon, Rectum and Anus
Once food has travelled through the small intestine, most of the essential nourishment has already been absorbed. What enters the colon is watery slurry. It passes through the ileo-caecal valve into a stretchy section of the colon called the caecum. The appendix hangs down from the caecum and is a relic, doctors believe, from when the human diet was far higher in plant matter than it is today. The appendix may have contained special bacterial agents that digest cellulose – much like grass-eating animals have. In the colon, water is reabsorbed from the watery slurry, making the waste more solid. What have now become faeces (‘poo’) slowly travel along the last portion of the colon until they reach the rectum, where they are expelled through the anus.
Bacteria flourish in huge numbers in the colon. Even though they are present in the stomach and the small intestines, there is generally too much activity (and acidity) in these areas for them to thrive. But in the colon, the waste passes through much more slowly and the environment becomes increasingly alkaline, allowing bacteria to multiply in vast numbers. However, these bacteria serve a useful purpose – not only do they help break down much of the remaining undigested material, but they also reduce the wind that is generated as waste slowly passes through the colon. There are exchanges of various hormones as well – for example, excess oestrogen in the blood is passed through the walls of the colon, and, if the diet is high in fibre, it binds to this fibre and can then be excreted. Otherwise, it would be reabsorbed back into the blood. Scientists now realize that too much of certain oestrogens in the body can be a contributory factor in the development of many ‘hormonal’ cancers – like breast cancer, ovarian and cervical cancers, even prostate and testicular cancers in men. Minerals can also be reabsorbed into the body here.
Food travels slowly through the colon – the average journey time is 12–48 hours to get through this 1½–2 metre (5–6ft) long tube. The colon walls secrete mucus to lubricate the waste matter and help it move along smoothly. In fact, mucus-secretion happens all the way along the gut – coming from a thin layer of cells called the mucous membrane. This membrane also protects the gut wall against bacteria and the acidity of the digestive enzymes, and helps ensure that it is our food and not our gut that gets digested when we eat. The rectum is about 15cm (6in) long and lies between the colon and the anal canal. It acts as a reservoir for the faeces. When it becomes full, nerve endings trigger strong muscular contractions that make us want to empty our bowels. This happens when the anal sphincter muscles open, allowing the waste to be expelled.
CHAPTER 2
Common Symptoms
Now we’ve had a quick glance at the anatomy of the digestive system, it is time to look at the symptoms that can indicate a gut problem.
This book cannot give you a definitive diagnosis – only your doctor can – but it can point you in the right direction. The self-help sections for each symptom offer practical advice on what you can do to help alleviate your problem.
Please note that you should always seek urgent medical help if any of the following occur:
Severe abdominal pain.
Acute diarrhoea and vomiting lasting more than 24 hours in the case of adults or 4–6 hours for infants, the elderly and anyone with a pre-existing medical condition.
Bleeding from the back passage.
Vomiting blood.
Constipation
‘Tell someone you’re constipated and sometimes they judge your personality more than your body. Phrases like “anally retentive” and “tight-arse” seem to spring into some people’s minds. I can almost see some people thinking it, although perhaps I’m oversensitive. But I’m not tight-arsed, I’m not hung-up or repressed, and I’m not scared of “letting go”. I do, however, have a problem with constipation!’
Adrian, 46, who regularly suffers from constipation
Constipation is not a disease, but simply a sign that our intestines are having trouble getting rid of compacted waste in our bowels. The majority of cases of constipation are caused by simple problems like dehydration, changes in routine (like travelling), ignoring the body’s ‘urges’ to go and even things like iron supplements and certain common medicines (like those containing codeine). Constipation can also happen during pregnancy, and is often associated with piles, or encopresis (a childhood problem). An underactive thyroid may also cause constipation, as can IBS and proctitis. Diverticular disease can be caused by chronic constipation. More serious, but also more rare, causes of constipation include intestinal obstruction, botulism poisoning, typhoid and paratyphoid, and bowel cancer.
Constipation is one of the most common afflictions of modern, westernized society – only 40 per cent of men and 33 per cent of women open their bowels regularly once a day and, according to surveys, over 4½ million Americans say they are constipated most or all of the time. Constipation is far less common in developing cultures where the diet is predominantly vegetarian. Highly refined and low-fibre products, fast foods and too many fatty or sugary foods are the main culprits of this problem.
There is also a mental element to constipation; a Gallup survey recently revealed that more than half of us are put off by the idea of using public toilets when out shopping and one in four of us feel the same hesitation over using toilets in restaurants or bars. The main reason for this is being unsure of the hygiene of public toilets – but there’s more to it than cleanliness. Millions of holidaymakers suffer with constipation. It’s a common phenomenon that has a lot to do with the disruption of routines and with being in unfamiliar circumstances. Stress may also play a part.
How Do You Know If You’re Constipated?
Bowel habits are an individual thing. Some people go twice a day, while others may go only every other day. Generally, anything between three times a day and three times a week is considered ‘normal’, although there are perfectly healthy people whose toilet habits fall outside even this broad range. ‘Normal’ is what is normal for you and not anyone else. Judge it by your own daily habits. Another sign of constipation is when you pass stools that are small and hard – so-called ‘rabbit pellets’.
What Helps Relieve Constipation?
Fibrous food adds bulk without calories – a bonus for anyone trying to lose weight – and also helps our intestines move digestive waste through (and out of) our bodies. Exercise, drinking plenty of water and increasing your fibre intake are often all that is needed to help remedy constipation. In developed countries people use laxatives far more often than necessary; laxatives can potentially aggravate things because they don’t address the root cause of constipation and may encourage the guts to become inactive without them. (Stimulant laxatives work by speeding up the muscular movements of our gut, forcing our waste food to be eliminated much more quickly than normal.) The same goes for enemas: according to the National Digestive Diseases Information Clearinghouse, the regular use of enemas ‘can impair the natural muscle action of the intestines, leaving them unable to function normally’.
Self-Help for Constipation
Fluids: Drink more water – aim for an intake of at least 2 litres (4 pints) of water daily. And watch your intake of tea and coffee as they may make constipation worse.
Fibre: Eating high-fibre foods as part of your everyday diet, is an easy way of alleviating chronic constipation (although some people suffering from IBS may find that fibre can aggravate their symptoms). However, be careful to increase your fibre intake slowly (especially with beans and pulses) – a rapid change can result in a marked increase in wind and abdominal discomfort, although this normally lessens as your guts get used to the change in diet. The recommended amount of fibre in the diet is about 20–35 grams a day. Try the following suggestions:
Choose wholemeal or added-fibre bread and pasta, brown rice and unrefined flour.
Eat more fruit and vegetables.
Bran can be added to the diet, especially cereals.
Flaxseed is a good source of soluble and insoluble fibre (3 grams per tablespoon, which is a lot), as well as contributing omega-3 fatty acids. Sprinkle it over salads and cereals or yoghurt to give a nutty taste. You can also substitute ground flaxseed for flour (in small quantities).
Dried apricots, desiccated coconut, dried peaches and toasted almonds are all very high in fibre and are convenient snacks.
Eat regular meals: The digestive system responds best when we eat little and often. Also try to have your main meal of the day at lunchtime to give it time to digest properly during the afternoon.
Exercise: A healthy, exercised body always functions more efficiently than an underactive one, and the bowels respond just as happily to exercise as our heart and cardiovascular system does. Even if it’s a brisk 30-minute walk three times a week, or a gentle swim, try and work exercise into your routine.
Don’t ignore urges: Try your best not to ignore the call of nature when you feel it. It’s difficult if you’re out, or cannot find a clean toilet, or are a shift worker whose body clock is all over the place, but do persevere all the same.
Establish helpful routines: The bowels love routine. If sitting on the loo with your daily newspaper for a few minutes every morning helps you get a regular routine going, then do it.
Avoid laxatives: Most people need to resort to laxatives every once in a while, but where possible they should be avoided – especially stimulant laxatives. Overuse of laxatives can lead to dependency, which is not healthy for the bowels and can cause unwelcome changes in the bowel if used for many years.
Herbal help: Laxatives – herbal or otherwise – are not a long-term solution to constipation but there are several herbs with mild purgative properties that can be used occasionally. Senna is the best known, but there are several others, including cascara, frangula, and yellow dock. They all contain special plant chemicals called anthraquinone glycosides, which have a laxative effect. Other herbs known for their ability to help relieve constipation include aloes, dandelion, liquorice, and rhubarb root. Ispaghula husk is an excellent natural bulking agent, which helps the body move waste food through the large intestine more easily. It should always be taken with lots of water.
Aromatherapy: Marjoram, rosemary and fennel oil may help; put a few drops into a base oil and gently rub onto the abdomen.
Homeopathy: There are several homeopathic remedies for various types of occasional constipation. These include lycopodeum, nux vomica, sepia, silicea, bryonia and alumina.
Further Information: National Digestive Diseases Information Clearinghouse, www.niddk.nih.gov/health/digest/pubs/const/const.htm and www.niddk.nih.gov/health/digest/pubs/whyconst/whyconst.htm For constipation in children, see Digestive Disorders Foundation, www.digestivedisorders.org.uk/Leaflets/adconsNEW.html
Laxatives – What Are They?
Laxatives are substances that encourage the bowels to open. They are extraordinarily popular – nearly $1 billion is spent on laxatives each year in the US. There are several types:
Bulking agents are concentrated fibre preparations that include bran, ispaghula husk, methylcellulose and sterculia. Brand names to look for include Fybogel and Isogel (UK), Metamucil and Citrucel (US). All bulking agents should be taken with plenty of water, as this helps them to swell and form their bulk, which in turn helps move waste effectively through the large intestine.
Stimulant laxatives encourage bowel movements by stimulating the nerve endings in the bowel walls to make the muscles contract. This speeding up of bowel muscles encourages waste to pass through more quickly. In doing so, less water is reabsorbed back through the bowel walls into the body, the stools retain more moisture, are less dense and compacted, and therefore easier to pass. Stimulant laxatives can cause diarrhoea if taken too often or in overdose and dependency can develop with overuse. They should not be used for longer than a week at a time and never given to children without a doctor’s specific advice. Brands include Dulco-Lax and Senokot (both UK and US).
Lubricants and stool softeners such as liquid paraffin, mineral oil and glycerine suppositories can be given to help soften hard, impacted faeces. They are most often used when haemorrhoids or anal fissures cause severe pain on straining.
Osmotic laxatives such as Epsom salts are used to attract more water into the bowel, which then softens hard stools. They can cause chemical imbalances in the blood and aren’t generally recommended for long-term use. Lactulose and sorbitol sugars also act as osmotic agents and are often used as an alternative to bulking agents in the long-term treatment of chronic constipation. Lactulose should never be used by anyone with lactose intolerance or milk allergy.
Diarrhoea
‘Everyone knows it – first, you get a gripey feeling deep in your belly, then you know you’ve got just a few seconds or less to get yourself into the nearest loo. It’s something that babies in nappies wouldn’t care about, but as an adult it becomes a real social problem. If it’s an acute case of food poisoning or holiday tummy it’s bad enough, but to have it constantly is a different ball-game altogether. It changes your life completely. You can’t go anywhere or do anything without military planning and knowing where every toilet is located. You become really good at inventing excuses and avoiding intimate situations. I’ve even had to resort to carrying spare underwear and wet wipes because of the odd disaster.’
Graham, 22, who suffers from severe, urgent diarrhoea caused by ulcerative colitis
Diarrhoea is defined as ‘frequent passing of abnormally loose or watery faeces’, and most of us easily know when we’re suffering from it! The urge to get to the bathroom quickly is normally a main feature and occasionally the first time we know we’ve got diarrhoea is when we’re ‘caught short’ or break ‘wet’ wind. Faecal incontinence (the medical term for being caught short) is more common than you might think, affecting one in 20 of us at some time or another.
Diarrhoea is often, though not always, accompanied by stomach cramps and, if it is caused by food poisoning, food intolerance or a flu-like illness, you may feel sick and throw up as well. Diarrhoea can be acute, starting suddenly and lasting only for a short period of time, or chronic and linger for weeks, months or years.
What Causes Diarrhoea?
The guts are very susceptible to developing diarrhoea – excess caffeine, vigorous exercise, excess fibre, excess alcohol, stress, antibiotics and even medicines and supplements (like iron, for example) can all cause it. Food intolerance and coeliac disease can also induce diarrhoea and in children it may be associated with a condition called encopresis. An overactive thyroid can cause diarrhoea, but so can viral gastroenteritis, parasitic infections, food poisoning, malabsorption, IBS, polyps and proctitis. While diarrhoea is far more likely to be caused by a minor problem, it can occasionally indicate more serious problems like ulcerative colitis, Crohn’s disease, diverticulitis, appendicitis, TSS, typhoid or paratyphoid, cholera and bowel cancer.
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